1. Field of the Invention
The present invention generally relates to an improved pulley set for doors and windows.
2. Description of Prior Art
Referring to FIG. 1, it shows a conventional pulley set 1 for doors and windows which comprises a housing 10 and a pulley stand 12 with a pulley 11 pivotally installed thereon. The pulley stand 12 is mounted inside the housing 10 to move obliquely along the housing 10 so that the pulley 11 is supported against the window frame. This conventional pulley set is characterized in that engaged in the pulley stand 12 is a nut board 13 which threads with an adjusting screw 14 that is rotatably fixed in the housing 10 and can only rotate at its original place. Rotating the adjusting screw 14 makes the nut board 13 to move relative to the housing 10, thereby pushing the pulley stand 12 to move obliquely along the housing 10 in order to adjust the height of the pulley 11 with respect to the doors or windows. However, the adjusting screw 14 of the conventional pulley set employs a special screw with a ring slot 140 between the head of the thread portion of the adjusting screw 14, and a metal plate 15 is engaged with the ring slot 140. Accordingly, when manufacturing, the adjusting screw 14 must require a process for forming the ring slot 140, which is not economic. In additions, the nut board 13 is not firmly engaged in the housing 10 and will shake easily when in use.
FIG. 2 shows another conventional pulley set 2 of doors and windows which comprises a housing 20, a seat 21, a pulley 22 and an adjusting screw 23, wherein the middle part of he housing 20 is provided with a pulley install portion 200 and the bottom plane thereof is an inclined plane 201 with an inclined angle and another side of the pulley install portion 200 is provided with an inclined guiding wall 202 with guiding slot 203 therein. The suitable place of the side of the housing 20 has a screw hole 204 for receiving an adjusting screw 23 and a groove 205 in which a washer 24 with the screw hole is inserted. The seat 21 with the pulley 22 pivotally mounted therein has an inclined plane 210 with engaging members 211 and another inclined plane 212 for corporation with the inclined plane 201 of the housing 20. The side of seat 21 is also provided with an inserting groove 213 for receiving a washer 25 inserted therein. When the seat 21 is installed in the pulley install portion 200 of the housing 20 for cooperating with the inclined plane 201, rotating the adjusting screw 23 will adjust the height of the pulley set 2. This conventional pulley set 2 requires inserting grooves 205 and 213 in the housing 20 and the seat 21 respectively for receiving the washers 24 and 25. However, the washers 24 and 25 made of metal not only increase the cost in manufacture for application but also require electroplating process for avoid rusting. Accordingly, there exits a need for providing an improved pulley set to overcome the problems mentioned above.
The present inventor has been engaged in the development and study of the structures of doors and windows for many years and understands and is familiar with the advantages and shortcomings associated with the conventional art. In views of problems mentioned above, the present inventor proceeded the study of improvement for the above shortcomings and invents an improved pulley set for doors and windows with more practice.
The primary object of the invention is to provide an improved pulley set for doors and windows, which is more stable in structure with reduced manufacturing cost
To achieve the above object, the pulley set in accordance with the present invention mainly comprises a base, a set, and adjusting means. The base can be engaged within or mounted on a groove at the bottom portion of doors and windows. The base forms a hollow space for receiving other elements and one side of the hollow space forms a vertical wall having a screw hole and the other side of the hollow space forms an inclined wall. A guiding plane parallel to the inclined wall extends from the vertical wall, and positioning slots are respectively formed in the guiding plane and the inclined wall. On top of the base is formed a clip piece so as to securely mount the base to the bottom of doors and windows. The seat is mounted within the hollow space of the base and both ends of the seat are respectively adjacent to the vertical wall and the inclined wall. The seat has a single or a plurality of pulley installed therein and two inclined planes and corresponding to the inclined wall and the guiding plane. Both the two inclined planes respectively have engaging bodies that can engage with the positioning slots formed in the inclined wall and the guiding plane such that the seat can move along the inclined wall and the guiding plane of the base. The adjusting means can utilize a screw or bolt disposed in the screw hole of the base. The end of the adjusting means will push against the side of the seat such that adjusting the adjusting means will cause the seat to move along the inclined wall and the guiding plane of the base.
When adjusting the height of pulley set relative to the door or window, the user merely rotates the adjusting means in the screw hole of the base. The end of the adjusting means will push against the side of the seat such that adjusting the adjusting means will cause the seat to move along the inclined wall and the guiding plane of the base with he engaging bodies sliding in positioning slots. Accordingly, the height of the pulley set with respect to the base and door or window can be raised lowered.